During World War II, the American military began investigating methods to protect the civilian population from domestic saboteurs. One solution the military devised was this extremely eerie Mickey Mouse gas mask.

These masks were designed to shield children from chemical warfare and to calm them with the dead-eyed visage of their favorite happy rodent. It would've been the precursor to an entire line of cartoon-themed gas masks. Explains former Army instructor Major Robert D. Walk of the mask's production:

On January 7th, 1942, one month after Pearl Harbor, T.W. Smith, Jr., the owner of the Sun Rubber Company, and his designer, Dietrich Rempel, with Walt Disney's approval introduced a protective mask for children. This design of the Mickey Mouse Gas Mask for children was presented to Major General William N. Porter, Chief of the Chemical Warfare Service. After approval of the CWS, Sun Rubber Products Company produced sample masks for review. Other comic book character designs were to follow, depending on the success of the Mickey Mouse mask [...]

The Sun Rubber Company produced approximately 1,000 Mickey Mouse gas masks and earned an Army-Navy ‘E' for excellence in wartime production in 1944.

Because of their small production run, these masks have since become collector's items — you can see an example from the Disney Archives at left. For more freaky old-school Disney regalia, see Serbian Donald Duck cosplay from the 1930s.